I ordered a Behringer 3-way active crossover...

http://www.behringer.com/CX3400/index.cfm?lang=ENG

....on Sunday, and it arrived yesterday. I've set it up for phase 1 of the
tri-amping project - splitting the top/mid from the bass. The following is
what I wrote last night in an email to a couple of mates. (For those that
don't already know, the Arcam Alpha is an original Mk1 version, and the
valve amp is a Maplin Millennium 4-20 kit that I built a few years ago.
Speakers are Kef B139/B110/T27 in home-brew reflex boxes with DN12
crossovers, and source is CD through a Meridian 203 DAC.)

---------------------
Currently, the Cyrus 2 is driving the bass, and I'm using the Arcam Alpha
for the top/mid. I disconnected the wires going to the bass driver, and
soldered them to binding posts - they are directly connected to the Cyrus,
with no passive crossover components between amp and speaker. The top/mid
are still being driven through the original Kef passive crossover, including
the bits that cut off the bass frequencies to the mid driver.

The Kef crossover frequency between bass and mid is 400Hz, but I've found
that setting the active crossover to this gave me a rather muddy sound on
the upper bass. Initial tweaking would suggest that something around
120-200Hz gives a better balance - need to play with this more.

Initial impressions are that the bass is more solid, and that the overall
sound is tighter. I'm surprised at the little Arcam Alpha - it's doing a
much better job with the top/mid than I expected. Gwyneth Herbert was quite
striking - she was bang in the middle of the speakers and very 'present' -
getting this with most music. Everything seems more 'coherent'.

There's a feeling that there's more low bass, but playing the test CD I made
with the sequence of single frequencies would suggest otherwise - the
noticable roll-off from about 60-70Hz downwards is still there. Whether the
roll-off will be as pronounced when the bass drivers are reboxed (and
doubled up) remains to be seen - I suspect there will still be losses at the
really low end, so I think some sort of EQ will eventually make its way into
the bass end.

Just swapped over to the valve amp after spending the last few hours using
the Arcam - it definitely has better resolution. There's more detail, and
everything sounds a bit more real, more 'open' - a better impression of the
acoustics of the recording room on some Sinatra tracks. The Arcam does seem
to put a veil over the sound. The problem with the valve amp is that it
doesn't produce its best at higher volumes - it seems to struggle a little
where the Arcam was coping better. The difference was apparent when I tried
Bailero by yon mezzosoprano at a fair old volume - her voice was a bit
roughish sounding through the Arcam, but more shouty through the valve amp
(it was this track that led me to change to the valve amp - the Arcam was
clearly not coping). Keeping the volume below the limits of the top/mid
amps, however, the valve amp kicks the **** out of the Arcam.

About the only downsides so far are a rather big pile of equipment, and a
fourth plateful of spaghetti hanging out the back. And the row of LEDs on
the crossover - these pro audio peeps need LEDs to tell them stuff about the
gear when in dark venues, but I could happily do without them. I'm thinking
of moving the power amps, the crossover, and the DAC out of the way (maybe
onto the corner of the desk), since I only really need the CD player, the
pre-amp and the Telewest box to be visible and easily accessible.

So far, then, the crossover looks like being a plus, with the potential for
being a serious improvement when the rest of the kit is sorted out.
---------------------

Been looking at more Behringer stuff this evening, and their Feedback
Destroyer thingy looks interesting - it also functions as a stereo 12-band
parametric EQ. Maker's product page is here...

http://www.behringer.com/DSP1124P/index.cfm?lang=eng

It's a DSP jobbie and, from what I can gather, each band can be set to any
frequency, and at 1/60th octave increments, no less. If it can function
slely as an EQ (ie, feedback-killer function switched off) I'm thinking of
getting one for the purpose of sorting out the bass response - it would go
between the crossover and the bass amp. Does anyone have any experience with
this bit of kit?


--
Wally
www.artbywally.com/FiatPandaRally/index.htm
www.wally.myby.co.uk

"Wally" wrote in message
...
I ordered a Behringer 3-way active crossover...

http://www.behringer.com/CX3400/index.cfm?lang=ENG

...on Sunday, and it arrived yesterday. I've set it up for phase 1 of the
tri-amping project - splitting the top/mid from the bass. The following is
what I wrote last night in an email to a couple of mates. (For those that
don't already know, the Arcam Alpha is an original Mk1 version, and the
valve amp is a Maplin Millennium 4-20 kit that I built a few years ago.
Speakers are Kef B139/B110/T27 in home-brew reflex boxes with DN12
crossovers, and source is CD through a Meridian 203 DAC.)

---------------------
Currently, the Cyrus 2 is driving the bass, and I'm using the Arcam Alpha
for the top/mid. I disconnected the wires going to the bass driver, and
soldered them to binding posts - they are directly connected to the Cyrus,
with no passive crossover components between amp and speaker. The top/mid
are still being driven through the original Kef passive crossover,
including
the bits that cut off the bass frequencies to the mid driver.

The Kef crossover frequency between bass and mid is 400Hz, but I've found
that setting the active crossover to this gave me a rather muddy sound on
the upper bass. Initial tweaking would suggest that something around
120-200Hz gives a better balance - need to play with this more.

Initial impressions are that the bass is more solid, and that the overall
sound is tighter. I'm surprised at the little Arcam Alpha - it's doing a
much better job with the top/mid than I expected. Gwyneth Herbert was
quite
striking - she was bang in the middle of the speakers and very 'present' -
getting this with most music. Everything seems more 'coherent'.

There's a feeling that there's more low bass, but playing the test CD I
made
with the sequence of single frequencies would suggest otherwise - the
noticable roll-off from about 60-70Hz downwards is still there. Whether
the
roll-off will be as pronounced when the bass drivers are reboxed (and
doubled up) remains to be seen - I suspect there will still be losses at
the
really low end, so I think some sort of EQ will eventually make its way
into
the bass end.

Just swapped over to the valve amp after spending the last few hours using
the Arcam - it definitely has better resolution. There's more detail, and
everything sounds a bit more real, more 'open' - a better impression of
the
acoustics of the recording room on some Sinatra tracks. The Arcam does
seem
to put a veil over the sound. The problem with the valve amp is that it
doesn't produce its best at higher volumes - it seems to struggle a little
where the Arcam was coping better. The difference was apparent when I
tried
Bailero by yon mezzosoprano at a fair old volume - her voice was a bit
roughish sounding through the Arcam, but more shouty through the valve amp
(it was this track that led me to change to the valve amp - the Arcam was
clearly not coping). Keeping the volume below the limits of the top/mid
amps, however, the valve amp kicks the **** out of the Arcam.

About the only downsides so far are a rather big pile of equipment, and a
fourth plateful of spaghetti hanging out the back. And the row of LEDs on
the crossover - these pro audio peeps need LEDs to tell them stuff about
the
gear when in dark venues, but I could happily do without them. I'm
thinking
of moving the power amps, the crossover, and the DAC out of the way (maybe
onto the corner of the desk), since I only really need the CD player, the
pre-amp and the Telewest box to be visible and easily accessible.

So far, then, the crossover looks like being a plus, with the potential
for
being a serious improvement when the rest of the kit is sorted out.
---------------------

Been looking at more Behringer stuff this evening, and their Feedback
Destroyer thingy looks interesting - it also functions as a stereo 12-band
parametric EQ. Maker's product page is here...

http://www.behringer.com/DSP1124P/index.cfm?lang=eng

It's a DSP jobbie and, from what I can gather, each band can be set to any
frequency, and at 1/60th octave increments, no less. If it can function
slely as an EQ (ie, feedback-killer function switched off) I'm thinking of
getting one for the purpose of sorting out the bass response - it would go
between the crossover and the bass amp. Does anyone have any experience
with
this bit of kit?

Never used the DSP1124 but I have a http://www.behringer.com/DSP8024/

great value for money!

Ben

Just bought another amp so going back to passive bi-amping, then maybe later
on could bypass
internal speaker crossovers. Just how much work is involved dialling in
crossovers on the rack unit? Ruark Epilogue speakers

I know Bryston make a active crossover..

http://www.bryston.ca/crossel.html

Pretty expensve though..

In article , Wally
wrote:
I ordered a Behringer 3-way active crossover...

[snip]

The Kef crossover frequency between bass and mid is 400Hz, but I've
found that setting the active crossover to this gave me a rather muddy
sound on the upper bass. Initial tweaking would suggest that something
around 120-200Hz gives a better balance - need to play with this more.

The 'crossover frequency' specified for most speakers is a fairly 'nominal'
value. Also, if you are simply splitting the links I assume the internal LP
and HP filters in the speakers are still in the signal paths. Thus the
'best' setting for your active crossover/filter may be quite different to
that specified for the speaker when used 'normally'.

Initial impressions are that

[big snip]

If you can make up CDs of test sinewaves, etc, and have access to a
reliable sound pressure meter, then it would be interesting to see to what
extent the differences you hear correlate with any changes in overall
frequency response being produced by the active crossover, differences in
gain of the two power amps, and effects of the output impedances of the
amps.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Ben wrote:

Never used the DSP1124 but I have a http://www.behringer.com/DSP8024/

Can't find it in the UK price list - what does it cost?


--
Wally
www.artbywally.com/FiatPandaRally/index.htm
www.wally.myby.co.uk

Nath wrote:
Just bought another amp so going back to passive bi-amping, then
maybe later on could bypass
internal speaker crossovers. Just how much work is involved dialling
in crossovers on the rack unit? Ruark Epilogue speakers

Very little, it would seem - connect the stuff up, select the right mode,
set all the gains to 0dB, tweak the crossover frequency(ies) until it sounds
right. Note that the Behringer uses XLR connectors - you'll need adapters if
you want to connect to kit that uses phono sockets.


I know Bryston make a active crossover..
http://www.bryston.ca/crossel.html
Pretty expensve though..

I'm very impressed with the Behringer so far - I half-expected some
softening of the detail, but, if anything, it all seems a touch better.
Amazing value at 90 quid delivered.


--
Wally
www.artbywally.com/FiatPandaRally/index.htm
www.wally.myby.co.uk

Jim Lesurf wrote:

The 'crossover frequency' specified for most speakers is a fairly
'nominal' value.

Yup, I can appreciate that.


Also, if you are simply splitting the links I assume
the internal LP and HP filters in the speakers are still in the
signal paths. Thus the 'best' setting for your active
crossover/filter may be quite different to that specified for the
speaker when used 'normally'.

No links as such - 3-way speakers with the bass drivers disconnected from
the passive crossovers and wired straight to the bass amp. The remaining
two-way pair are still connected to a single amp, going through the full
3-way crossover (with the LF output open circuit).

I'm thinking of converting to the two-way Kef crossover for splitting the
B110 and T27 (this version has no high-pass element on the B110 cct, since
the B110 is acting as bass and mid in a two-way set up). The B110 is in its
own IB sub-enclosure within the main cabinet. Do you think this is worth
pursuing, or would there be some sort of 'conflict' of B110 roll-off in the
sub-enclosure, compared with the 24dB/octave low-pass that the active
crossover applies to the bass driver?


If you can make up CDs of test sinewaves, etc, and have access to a
reliable sound pressure meter, then it would be interesting to see to
what extent the differences you hear correlate with any changes in
overall frequency response being produced by the active crossover,
differences in gain of the two power amps, and effects of the output
impedances of the amps.

Urrr..., I can make test CDs of sine waves. :-) (With a bit of software I
had on my old computer - would need to find it and reinstall.) Don't have a
sound pressure meter, I'm afraid. I suppose the Cyrus 2 has more gain than
the valve amp. I think their input sensitivities are roughly similar
(200-300mV for full power). The valve amp (20-ish Watts) is set to half
volume, the Cyrus (50W) at about '3', and the gains/cuts on the active
crossover are all set to 0dB. This seems to produce a balanced sound. The
overall volume is controlled by a preamp.

It's all calibrated with the indubitably dubious power of the human
lug-'ole - but it's my lug-'ole, and that's the one that matters. :-) My
impression of the Behringer is that it's essentially flat - without a set of
before and after measurements, I'm assuming that the feeling of better
clarity and improved bass is down to having more power available, and
perhaps splitting bass and mid/top to separate amps.


--
Wally
www.artbywally.com/FiatPandaRally/index.htm
www.wally.myby.co.uk

"Wally" wrote in message
...
Ben wrote:

Never used the DSP1124 but I have a http://www.behringer.com/DSP8024/

Can't find it in the UK price list - what does it cost?


--
Wally
www.artbywally.com/FiatPandaRally/index.htm
www.wally.myby.co.uk

£90-£110. Used to EQ your sub, but can be used full-range EQ as well.

Nath wrote:

£90-£110. Used to EQ your sub, but can be used full-range EQ as well.

The DSP1124 is about 70-90 quid, but doesn't seem to have that RTA
calibration thingy. From what I can gather, you connect a mic to the 8024,
hit a few buttons, and it sets up the graphic to give a flat (or
otherwise-specified) response? I wasn't really thinking of full-range EQ,
just the bass, which was why I thought the 1124 would be a better idea - the
12 parametric bands can all be bunched at the low end. That said, the 8024
looks like it might do the business anyway, given that it has 3 1/60th
octave parametrics as well. It also has better specs...

-------------------------
8024:
Bandwidth 20 Hz to 20 kHz (+0/-0.5 dB)

Signal to Noise Ratio 103 dB unweighted, 22 Hz to 22 kHz

THD+N 0.004 % @ 1 kHz / +4 dBu

Crosstalk -103dB, 22 Hz to 22 kHz

-------------------------
1124:
Bandwidth 20 Hz to 20 kHz, -3 dB

Noise 94 dB, unweighted, 20 Hz to 20 kHz

THD 0.0075 % typ. @ +4 dBu, 1 kHz, Gain 1

Crosstalk -76 dB

-------------------------

Could you suggest a UK supplier for the DSP8024? Google doesn't seem to be
revealing any.



--
Wally
www.artbywally.com/FiatPandaRally/index.htm
www.wally.myby.co.uk

Lots of info here about 1124p, it is used for LF EQ'ing..

http://www.snapbug.ws/bfd.htm

if you want more advanced PEQ for full-range, also checkout 2496.

http://www.behringer.com/DEQ2496/index.cfm?lang=ENG